💿🐜 Antkeeper source code
https://antkeeper.com
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107 lines
3.1 KiB
107 lines
3.1 KiB
/*
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* Copyright (C) 2020 Christopher J. Howard
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*
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* This file is part of Antkeeper source code.
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*
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* Antkeeper source code is free software: you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* Antkeeper source code is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with Antkeeper source code. If not, see <http://www.gnu.org/licenses/>.
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*/
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#ifndef ANTKEEPER_CELESTIAL_MECHANICS_HPP
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#define ANTKEEPER_CELESTIAL_MECHANICS_HPP
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#include "utility/fundamental-types.hpp"
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namespace ast
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{
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/**
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* Contains six orbital elements which describe a Keplerian orbit.
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*/
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struct orbital_elements
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{
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double ec; ///< Eccentricity, e
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double a; ///< Semi-major axis, a
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double i; ///< Inclination, i (radians)
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double om; ///< Longitude of the ascending node, OMEGA (radians)
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double w; ///< Argument of periapsis, w (radians)
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double ma; ///< Mean anomaly, M (radians)
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};
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/**
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* Orbital state vectors.
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*/
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struct orbital_state
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{
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double3 r; ///< Cartesian position, r.
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double3 v; ///< Cartesian velocity, v.
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};
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/**
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* Approximates the obliquity of the ecliptic.
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*
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* @param jd Julian date.
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* @return Obliquity of the ecliptic, in radians.
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*/
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double approx_ecliptic_obliquity(double jd);
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/**
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* Approximates the ecliptic coordinates of the Earth's sun.
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*
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* @param jd Julian date.
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* @return Ecliptic rectangular geocentric coordinates of the Earth's sun, with distance in AU.
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*/
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double3 approx_sun_ecliptic(double jd);
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/**
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* Approximates the ecliptic coordinates of the Earth's moon.
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*
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* @param jd Julian date.
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* @return Ecliptic rectangular geocentric coordinates of the Earth's moon, with distance in Earth radii.
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*/
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double3 approx_moon_ecliptic(double jd);
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/**
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* Approximates the ecliptic rotation of the Earth's moon.
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*
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* @param jd Julian date.
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* @return Rotation matrix representing the moon's rotation in ecliptic space.
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*/
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double3x3 approx_moon_ecliptic_rotation(double jd);
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/**
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* Iteratively solves Kepler's equation for eccentric anomaly, E.
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*
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* @param ec Eccentricity, e.
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* @param ma Mean anomaly, M (radians).
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* @param tolerance Tolerance of solution.
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* @param iterations Maximum number of iterations.
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* @return Eccentric anomaly.
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*/
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double solve_kepler(double ec, double ma, double tolerance, std::size_t iterations);
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/**
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* Calculates the ecliptic rectangular orbital position from Keplerian orbital elements.
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*
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* @note Only works for elliptical orbits.
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*
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* @param elements Orbital elements.
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* @param ke_tolerance Kepler's equation tolerance.
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* @param ke_iterations Kepler's equation iterations.
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* @return Orbital state.
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*/
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double3 orbital_elements_to_ecliptic(const orbital_elements& elements, double ke_tolerance, std::size_t ke_iterations);
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} // namespace ast
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#endif // ANTKEEPER_CELESTIAL_MECHANICS_HPP
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